Global Var

Maybe can be a problem of my small micro?

Most likely not. I would guess it is a problem with the code, but lacking the code it is hard to verify that.

What do u think about this?

I think that given the scarcity of information, any statement about the nature of the problem can be classified as speculation.

SPid iA

void PIDa (void) _task_ A _priority_ 1 {

        Ua = UpdatePID (&iA, SPa, PVa, 1, 4);

        os_send_signal(WRITE);

        os_delete_task(A);


}

iA is my global var that it is initialized into a task. This task is calling to the task A (top).

When UpdatePID funtion is executed the iA var not update.

What do u think about this?
I have no idea what micro (u) think about this, what I think is that you are trying to run before you have even learned to crawl, that is a surefire way of breaking a leg.
learn to crawl, THEN learn to walk, THEN learn to run.
1) read "the bible" and the datasheet for your device a couple of times to familiarize yourself with the contents.
2) work through (I did NOT say 'read') the Keil "getting started guide"
3) do some simple projects (start with 'blinky') gradually adding complexity
4) go back to whatever running it is you are trying to do way too early.

Erik

You show a global variable of an unknown data type.

You show that you send the address of the variable to a function.

You do not show the function implementation

Exactly what do you think will be able to deduce from this?

I am not sure I understand what you are doing here: are you terminating the task that does your PID calculations just after one cycle? this is not the way to implemented a closed loop using a PID controller, of any controller whatsoever that is based on feedback.

that is being wise words of wisdom from the very wise old man!!!!!!

The data type is :

typedef struct {

real dState;            /* Ultima posicion             */
real iState;            /* Estado del integrador       */
real uMax,uMin;     /* Saturacion del actuador     */
real Kp;                    /* Ganancia proporcional       */
real Ti,Td;                     /* Cte, tiempo integral y derivativo        */
real Ts,Tt;                     /* Periodo muestreo, Cte. tiempo tracking   */
real Kwindup;           /* Cte. antireset windup                    */

} SPid;

The funtion implementation i think that is not important to resolve my problem. This is the top of the funtion:

real UpdatePID (SPid *pid, real SP, real PV, unsigned int AUTO,real Uman) reentrant;

real is int data type

Hi Tamir,

My idea is:
- I have a WRITE task that initialize the PID task:

                  os_create_task(A);
                  os_create_task(B);
                  os_create_task(C);

                  os_wait(K_SIG, WAIT_FOREVER,0);       /* Espera hasta que algun PID actualice el valor */
                  os_clear_signal(WRITE);

This 3 task should update my global var called iAiBiC respectly.

After i send the result of the PIDs to serial port for comunications with a simulator.

For Erik!!

What is your problem???????
Im a student and i work too hard to learn it.
If you dont want response my problem is not necesary your answer!!!!

Good luck!!

java,

you must be please excuse sir erac becasue he is sometimes makeing joke he thinking is funng but is not funny and is lokking very bad you be thinking!!!!!

pleaes remember he is very old and wise and he wanting respect from every one and he may be sometimes he giving good ansewr.

Tamir!

How you implement a PID in a task to controller a system??
Thanks

Erik Did respond. He noted - as several others - that you supplied to little info for anyone to come with suggestions. He also noted that you seemed to be doing things you where not comfortable with, and I would think most other readers would agree.

I asked you for the function implementation, since it is the function that will assign any new values to your global variable. By the way - why a pointer to a global variable? Do you have multiple global variables of the same type, and sometimes send the address to one variable, and sometimes the address to another?

You said: "The funtion implementation i think that is not important to resolve my problem."

If the function does not perform any assign using the pointer, then your global variable will not be updated. Obviously the implementation of the function seems to be very, very relevant, don't you think?

Another thing - real is int? Is that your own data type, or an assumption about the Keil float? Every programmer who sees the name "real" will map into their brain the very obvious notation that real is NOT an integer. A real should be a floating point value - or in some situations maybe a fixed-point value. But when you work with finite-resolution fixed-point values, you normally name them according to their size, just so you always know how many decimals you have. This is very important when multiplying two fixed-point numbers which produces twice as many decimals as the original numbers had.

OK!!sorry.

Thanks Per!!!

real is my data type, now is int but i created this for future changes.

The implementation is important Yeah!!! but i think that it is OK:

error = SP - PV;

                P = pid->Kp*error;
                if (pid->Ti){
                        I = pid->iState*(pid->Kp*(pid->Ts/pid->Ti)+ pid->Kwindup);
                        pid->iState = pid->iState + error;
                }else I=0;
                if (pid->Td){
                        D = (pid->Kp*(pid->Td/pid->Ts)*(PV - pid->dState));
                        pid->dState = PV;
                }else D=0;
                v = P + I + D;

this is a piece of code.
For example the pid->iState it is not updated!!!

I dont know where is the problem.

Have you made sure that your function thinks pid->Ti is non-zero, so it has a reason to update pid->iState?